Good series of articles about Windows 7 security:
http://www.windowsecurity.com/articles/Windows-7-Security-Primer-Part1.html
http://www.windowsecurity.com/articles/Windows-7-Security-Primer-Part2.html
http://www.windowsecurity.com/articles/Windows-7-Security-Primer-Part3.html

These articles cover the fundamental information how to secure Windows 7 and some of the lesser known security functionality it provides.

- Urs